End closure for explosive cartridges



4 c. R. JOHNSON ETAL 2,326,310

END CLOSURE FOR EXPLOSIVE CARTRIDGES Filed March 9, 1959 2 Sheets-Sheet 2 Charles RJbkZZI'OZ? illzam d. Pile/2e!" INVENTORS Charles lidzanlqg 13/ ATTQRNEY Patented Aug. 10, 1943 UNITED STATES PATENT. OFFICE END CLOSURE FOB. EXPLOSIVE CARTRIDGES Charles Russell Johnson, Glen Mills, Pa and rlliam Stanton Pilcher,

Woodbury, and

Charles Belton Stanley, Paulsboro, N. .L, assignors to E. I. du Pont de Nemours & Company, Wilmington, Del., a. corporation of Delaware l lllication March 9, 1939, Serial No. 260,694

1 Claim. (Cl. 102-24) because of the tendency of the loaded shell to spring open, permitting ingress of water and often occasioning a loss of some of the explosive charge.

The object of the present invention is the pro-' duction of an improved shell closure by a facile method. Another object is a method and apparatus which permit efiicient formation of a closure of increased mechanical strength. A further object is a device adapted to produce improved interlockingfolds in the shell material. Additional objects will be disclosed as our invention is disclosed more fully hereinafter.

The foregoing objects are accomplished by the use of apparatus of novel design to produce an improved closure of depressed interlocking folds, in accordance with the method herein described. In order that the invention may be understood more clearly, reference is made to the accompanying drawings which illustrate a specific embodiment of my invention without limiting the scope thereof.

Referring generally to the various figures, Figure 1 s a pl n view partly in perspective and partly in cross-section of a member adapted to restrict the shell wall and to form folds at spaced intervals therein. Figures 2 and 3 are vertical views in cross-section on the lines 33 and 22, respectively. A vertical view in perspective of a tamping means adapted for use inconjunction the closure. Figure 8 is a side view of the improved crimp or closure produced on the end of the shell. Figure 9 is a view of the device in operation on a dynamite shell.

Similar numerals refer to similar parts throughout the several views.

. Referring more specifically to Figure 1, which isa cross-sectional view from the side of the folder member which first engages the dynamite shell, the numeral l denotes the circumference on which lie the outermost points of the working surface. Said folder device may beconstructed of wood, synthetic resins, non-sparking metal, and the like. The surface 3 between said circumference and the curved lines 2 is flat or even and does not enter into the operation of folding the shell. Starting with the curved lines 2, the surfaces 4 slope downward and inward in the manner of the inner surface of a cone, viewed from its base toward the tip. The angle of incllnation in the present embodiment is 45 with respect to the horizontal axis, and may be observed more readily by referring to Figures 2 and 3. The conical surfaces 4 extend to 5 the perimeter of the cylindrical portion of the folding device, said portion being designated by the numeral 6. Rather deep grooves I extend diagonally down through both the conical and cylindrical surfaces, in a manner somewhat similar to a spiral, said grooves being characterized by one wall which rises in a substantially vertical plane with respect to the surfaces 4, said wall being shown by the numeral 9 in Figure 3.

The method of operationis as follows: A cartridge loaded with a dynamite composition, but having one end open, isbrought into contact with a folding member of proper size. The circumference of the dynamite shell in such case is approximately intermediate in size between the circumference l of the cone, and the circumference 5 of the cylinder. Duto the fact that the surfaces 4 are in different planes, the shell wall contacts the aforementioned vertical walls 9 of the grooves I at a point inside the outer ex-.

terial to crease, whereas contact of the remainder of the surface of the shell with the remainder of surfaces 4, forces the top of the resulting folds or pleats into the grooves I. In this manner the open end of the shell is restricted to a crosssection corresponding'to that of the cylinder 6, and, ispharatteiikd by a,numb,er of folds corresponding to the number of grooves, said folds inclining toward the center and lying at an angle of about 45 with respect to the longitudinal axis of the shell, so that a spiral effect is produced. Due to the aforementioned inclination, the uppermost tips of the folder shell are closely Grouped.

-ing pin is illustrated in Figures 4 and 5. The

construction shown therein involves a rod l acting wtihin a sleeve ll, said sleeve being provided with slots II, which permit the escape of excessive moisture-proofing agent, as paraffln, for example. The slot i2 permits an original engagement of the base of the sleeve I 5 which is independent of the enclosed rod, the pin l3 acting as a stop as well as a means of retention of the sleeve during operation.

The details of the base of the tamping member are shown in Figure 5. It will be noted that the flat surface ID of the sleeve is quite small in cross-section, the remainder of the sleeve wall I! having a receding surface which slopes inward. This particular design is well adapted to prevent slippage of the folds of the cartridge during the tamping operation.

In actual operation, a spring or other suitable tension member is slipped over the top part of the tamping pin which is then placed in a fixed position by inserting that portion of the rod having a reduced cross-section into a carrying member having an aperture adapted to retain the same. Such arrangement is illustrated in Figure 6. The spring l9 then rests snugly between the sleeve and the carrying member l8, and exerts sufficient pressure to cause the base of the sleeve to extend beyond that of the rod. Thus, when the tamping operation commences, only the retaining base of the sleeve engages the shell folds at flrst, the sleeve then being forced upward against the tension of the spring as the pressure increases, the rod being contacted only after said spring has been compressed a predetermined degree. In this manner a uniform, conical crimp of interlocking folds is formed. The sleeve, which of course contacts the wrapper material in advance of the pin, may be brought forward to strike the material directly, or may be brought forward with a twisting motion by rotating the same about its axis at the time of contact with the wrapper. The latter is preferable.

In Figure 9 the entire assembly is depicted, showing the relative position of the various parts at one point in the operation of crimping the end of a charged dynamite shell. Thus the open end 20 of the shell 2| is shown folded inwards toward the cylinder 6 by contact with the various elements of the folder device as described. The tamping pin is depicted as disposed within the cylinder 6 and approaching the gathered folds, showing the sleeve in advance of the pin.

Figure 8 depicts the resulting crimp which is conical in shape, uniform in structure and comprises interlocking folds of shell material so that springing open of the crimp is avoided. A is a round head or reversed fold in the paper side walls of the cartridge. B is a sharp bend in the wrapper material. C is the point at which the raw edges of the fold meet. D is the point at which the raw edges of the material double back on themselves. In producing said improved and closure with depressed interlocking folds, displaying increased strength, the following factors should be considered. The reverse bend A should be as sharp as practicable. The smaller the radius at A, the greater is the tendency of the closure to stay in place. The folding pin should be shaped to produce a sharp break at B, eflecting a line or bead approximately concentric with the cartridge wall. The end of the folding pin should bulge to produce a depression in the central .portion of the fold at C,-which extends deeper into the powder than at B, thus effecting a somewhat conical structure and adding strength to the fold. Each fold or flute of paper D should overlap the adjacent fold E, and so on around, forming a regular figure about the center. Preferably, the line of the fold determined generally by the points A, B and D, should be as near a radial line as is practicable, for the purpose of.adding structural strength. The degree with which this fold approaches a radial line is determined by the number of flutes or folds around the center and by the shape of the tool causing the fold to be formed.

The apparatus described in the foregoing is particularly well adapted to machines employed for loading simultaneously a plurality of dynamite shells. because the folding membersas well as the tamping pins may be provided readily in series in such manner that they coincide with the spacing of the cartridges during the loading operation. Hence, after the explosive has been charged into the shells, it is a simple matter to engage the top of said shells with a member provided wtih the folding and tamping members in the requisite position.

In operating in accordance with our invention, it is not necessary to restrict the grooves in the folding member to a definite number, because the number most advantageous for the operation is influenced by various factors, among which may be mentioned the physical characteristics of the flexible shell material and the physical properties of the explosive charged into the shell. Nor need the grooves be maintained at a definite depth, it being possible to obtain satisfactory results with variations in depth, depending on the diameter of the shell, and the stiffness and weight of the material, of which said shell is constructed. These possible variations in design, however, can be determined by experiment.

Likewise, the extension of the shell wall beyond the level of the explosive charge depends on the size of the shell being closed. For example, where it is-desirable to close a shell 1 /2 inches in diameter, we have found that a very satisfactory end closure may be obtained if the level of the explosive charge be of an inch below the edge of the shell wall. For a shell having a diameter of 1% inches, of an inch has proved satisfactory.

In operating in accordance with our invention, a uniform crimp, characterized by interlocking folds, is obtained. Such closure possesses a mechanicalstrength materially greater than closures of similar class which were known heretofore, and hence permits enclosure of the various dynamite compositions currently manufactured, without danger of loss of the explosive charge because of accidental opening of the shell.

Furthermore, the end closure produced by the method and apparatus of our invention offers the additional advantages that it displays an increased water resistance, and enhanced imperviousness to moisture over closures of the art. In addition this closure lends itself more readily to the various water-proofing and moisture-prooflng methods such as the operations of end spraying, coating or dipping with waterproofing or sealing compositions.

and interlocking folds in said wrapper originating at the central portion of the end of said cylindrical charge and extending to the circumference thereof, the surface defined by said folded wrapper being characterized by a marked depres- I sion in said central portion whereby the said sharp bend and the said marked depression cooperate to hold the folded closure in place and prevent the individual folds from springing away 10 from the explosive charge.

CHARLES RUSSELL JOHNSON. WILLIAM STANTON PILCHER. -CHARLES BEL'ION STANLEY. 

